Bunuel
Flagpole Army Base in Oregon and Klondike Army Base in Alaska are similar bases with similar duty loads. Despite the similarities, Klondike always has had more men than Flagpole has. Clearly, each soldier at Klondike must have to perform a smaller share of the duties, and therefore soldiers at Klondike must have more free time than do soldiers at Flagpole.
In evaluating the argument, it would be most useful to know which of the following?
(A) Whether those recruits who are in a position to choose, choose Flagpole over Klondike.
(B) Whether the officers administering the Flagpole and Klondike bases have had similar training.
(C) Whether the morale level at Klondike is higher than the morale at Flagpole.
(D) Whether regular furloughs from Klondike are longer than furloughs from Flagpole, to account for added travel time.
(E) Whether similar numbers of soldiers are stationed at comparable bases throughout the country.
OFFICIAL EXPLANATION
We are only told about similarities between Flagpole & Klondike bases. The conclusion seems assume their complete similarity. Is it true that the two bases are similar in every meaningful way? Or is there some difference that would be meaningful as to time on duty and staffing? That's what we need to know?
(D) is the credited answer. If furloughs from Klondike are longer, that means at any one time, there will be more men from Klondike on leave than would be on leave at another base; this, in turn, means fewer staff people would be on base at Klondike to perform duties. Therefore, to ensure the same duty load as other bases have, Klondike would have to have more men assigned to it. This logically explains the discrepancy by supplying a meaningful difference.
(A) & (C) are only weakly suggestive, and both can be determined by a wide variety of other factors. Many factors can determine which base a new recruit would prefer, and many factors would determine morale at a base. Neither would allow for a strong conclusion either way about this argument.
As for (B), we suspect that army officer training is relatively standardized throughout the country, that there would be no meaningful difference in the overall officer training at one base vs. another. In particular, it's very hard to imagine any training regimen for officers that would say routinely giving men a great deal of extra free time beyond what is standard is a good idea. It's not reasonable to expect that anything involving difference in officer training would account for the staffing differences at these two bases.
As for (E): we already know there is a difference between the number of assigned to Flagpole and to Klondike. Knowing how many men are assigned to bases in general would give us a better idea which one of these two bases is further from the average, but it wouldn't shed light specifically on why they are staffed differently.